DK2297815T3 - ROTOR SHEET WITH INTEGRATED RADAR ABSORBER FOR A WINDOW POWER PLANT - Google Patents

ROTOR SHEET WITH INTEGRATED RADAR ABSORBER FOR A WINDOW POWER PLANT Download PDF

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Publication number
DK2297815T3
DK2297815T3 DK09749491.8T DK09749491T DK2297815T3 DK 2297815 T3 DK2297815 T3 DK 2297815T3 DK 09749491 T DK09749491 T DK 09749491T DK 2297815 T3 DK2297815 T3 DK 2297815T3
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DK
Denmark
Prior art keywords
rotor blade
radar
absorber
power plant
radar absorber
Prior art date
Application number
DK09749491.8T
Other languages
Danish (da)
Inventor
Joachim Bettermann
Andreas Frye
Original Assignee
Airbus Defence & Space Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Airbus Defence & Space Gmbh filed Critical Airbus Defence & Space Gmbh
Application granted granted Critical
Publication of DK2297815T3 publication Critical patent/DK2297815T3/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D1/00—Wind motors with rotation axis substantially parallel to the air flow entering the rotor 
    • F03D1/06—Rotors
    • F03D1/065—Rotors characterised by their construction elements
    • F03D1/0675—Rotors characterised by their construction elements of the blades
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D80/00—Details, components or accessories not provided for in groups F03D1/00 - F03D17/00
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D80/00—Details, components or accessories not provided for in groups F03D1/00 - F03D17/00
    • F03D80/10—Arrangements for warning air traffic
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2260/00—Function
    • F05B2260/99—Radar absorption
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2280/00—Materials; Properties thereof
    • F05B2280/60—Properties or characteristics given to material by treatment or manufacturing
    • F05B2280/6003—Composites; e.g. fibre-reinforced
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2280/00—Materials; Properties thereof
    • F05B2280/60—Properties or characteristics given to material by treatment or manufacturing
    • F05B2280/6011—Coating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2280/00—Materials; Properties thereof
    • F05B2280/60—Properties or characteristics given to material by treatment or manufacturing
    • F05B2280/6013—Fibres
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2253/00—Other material characteristics; Treatment of material
    • F05C2253/04—Composite, e.g. fibre-reinforced
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2253/00—Other material characteristics; Treatment of material
    • F05C2253/12—Coating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2253/00—Other material characteristics; Treatment of material
    • F05C2253/16—Fibres
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction

Landscapes

  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Sustainable Energy (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Wind Motors (AREA)

Description

Description
The invention relates to a rotor blade of fiber-reinforced plastic for a wind power plant. To reduce radar reflection, it comprises a passive radar absorber integrated in the surface. A moving object is generated by the movement of wind energy rotors and/or the rotor blades for radar systems of air traffic control, which, as 2-D radar systems, require the direction and the distance of a flying object for the display. The rotor blades as moving objects are characterized, like aircraft, by a sufficiently strong reflection having Doppler components. Additional moving targets are thus generated for the radar, which obstruct or corrupt the display of a flight lane of an actual flying object.
Interference absorbers and Jaumann absorber constructions, which reduce radar reflection, are known from earlier patent applications, for example, DE 199 29 081 Al, which ensure a particularly high-quality radar reflection reduction. Due to the very large radar cross section of a wind power plant of greater than 400 m2, however, a sufficient reflection damping of greater than 20 dB in the operating frequency range of radar systems for air traffic control is not ensured under all weather conditions. All previous solutions and production methods share the feature that all reflection-relevant surface regions advantageously display a reflection-damping effect. DE 39 01 012 Al describes the rotor blade of a helicopter, wherein an erosion-reducing lining is provided in the region of its front edge, which consists of a material that absorbs electromagnetic radiation.
Various radar absorbers are described in Paul Saville: "Review of Radar Absorbing Materials" Defence R&D Canada-Atlantic No. TM 2005-003, 3 January 2005 (2005-01-03), Dartmouth, NS, CA retrieved from the Internet: URL: http://www.dtic.mil/cgi-bin/GetTRDoc? AD=ADA436262&Location=U2&doc=GetTRDoc.pdf (retrieved on 2009-08-18), inter alia, also the Salisbury screen and the Jaumann absorber.
The object of the present invention is to ensure by the specific use of a radar absorber that the radar system recognizes the wind power plant as such and can differentiate it from an actual flying object.
This object is achieved by the subject matter of patent claim 1. Advantageous embodiments of the invention are the subject matter of dependent claims.
According to the invention, the passive radar absorber embedded in the fiber-reinforced plastic material of the rotor blade comprises the following elements: • a layer close to the surface, in particular formed from a fibrous web, cloth, knitted fabric, or a film. It has a defined electrical sheet resistivity of 100 to 800 ohm/square and is located at a depth of 2 to 5 mm below the surface of the rotor blade; • a layer far removed from the surface at a distance of 5 to 16 mm to the layer close to the surface. The layer far removed from the surface can also be formed as a fibrous web, cloth, knitted fabric, or a film. The layer far removed from the surface is a technically conductive layer with a defined electrical sheet resistivity of a maximum of 50 ohm/square.
The integrated radar absorber is selectively restricted to one or multiple discrete surface sections, i.e., surface sections separated from one another, of the rotor blade, without covering the entire surface of the rotor blade and without extending along the entire length of the rotor blade.
According to the invention, in at least one the discrete surface sections on which the radar absorber is provided, one section of the rotor blade edges is located.
In one embodiment, in each of the discrete surface sections on which the radar absorber is provided, one section of the rotor blade edges is located.
This absorber construction according to the invention ensures a monostatic reflection reduction in a restricted angle of incidence range.
Since the radar absorber does not have to cover all reflectionrelevant surface sections, advantages result with respect to material consumption and weight.
Due to the selective arrangement of the radar absorber on one or multiple isolated surface sections of the rotor blades, a defined time-dependent reflection intensity is generated during a rotation of the rotor, the characteristic of which enables the signal processing of a radar system to identify this object as a wind power plant and filter it out. The tracking of an actual flying object is not thus impaired.
The quality of the reflection damping of the radar absorber and the surface use of the radar absorber with respect to the shaping, the dimensions of the rotor blade, and the rotational velocity of the rotor enable a defined time dependence of the reflection intensity in the direction of the radar system to be ensured.
The starting materials generally used for these materials (resin or polymer matrix; carbon, glass, or aramid fibers) can be used for the fiber-reinforced plastic material
To set the required electrical sheet resistivity of 100 to 800 ohm/square for the layer close to the surface of the radar absorber, commercially-available fiber materials of low electrical conductivity can be adapted accordingly, for example, by weaving in metallic threads or by coating the fiber material with conductive materials.
To be effective for specific polarization directions of the radar system, the layer close to the surface of the radar absorber can advantageously comprise a preferred orientation in the surface, which causes an orientation-dependent surface conductivity. This can be achieved, for example, by differences in the fiber compaction or in the fiber diameter.
The invention will be explained in greater detail on the basis of multiple figures. In the figures:
Figure la shows the illustration of the time dependence of the radar cross section of a wind power plant without radar absorber according to the invention;
Figure lb shows the illustration of the dynamic radar cross section, which is detected by a radar having a revolution period of 4.2 seconds, of a wind power plant without radar absorber according to the invention;
Figure 2a shows the illustration of the time dependence of the radar cross section of a wind power plant with radar absorber according to the invention;
Figure 2b shows the illustration of the dynamic radar cross section, which is detected by a radar having a revolution period of 4.2 seconds, of a wind power plant without radar absorber according to the invention;
Figure 3a shows the construction of a radar absorber according to the invention, integrated into the rotor blade of a wind power plant;
Figure 3b shows the frequency response of the reflection reduction (in dB) of the radar absorber according to the invention as shown in Figure 3a.
Figure 4 shows a rotor blade according to the invention in three views :
Figure 4a 3D illustration Figure 4b sectional illustration Figure 4c top view.
Firstly, the functional principle of the radar absorber according to the invention will be explained on the basis of Figures 1 and 2.
Figures la and lb relate in this case to a rotor without radar absorber according to the invention. Figure la shows the time dependence with which a wind power plant is detected by a radar over a period of time of 10 seconds (in the case of continuous illumination). A cyclic curve having broad maxima which vary strongly can be recognized because of the rotor movement.
Figure lb shows an illustration of the dynamic radar cross section of the wind power plant detected by the radar over a period of time of 60 seconds in arbitrary units (for simplification, only the rotor blade shown above is considered, with the assumption that the rotor blade supplies interfering reflection contributions along its entire extension). The radar has a revolution period of 4.2 seconds here, i.e., the radar only detects the wind power plant in successive points in time having a time interval corresponding to its revolution period. Accordingly, pronounced radar reflections at intervals of approximately 4.2 seconds each can be seen in Figure lb. If one takes a value of 200 units on the vertical axis as a threshold value, the radar reflection of the wind power plant is thus only absent 2 times (at approximately 17 seconds and 38 seconds) within 60 seconds in the illustrated measurement. The tracking of the target by the radar is not impaired by such individual absences of the radar echo, however. The wind power plant is therefore interpreted by the radar as a moving target.
Figure 2a and Figure 2b show the corresponding graphs for a wind power plant with rotor blades according to the invention, i.e., with radar absorber integrated therein. A comparison of Figure 2a to Figure la shows that a) the absolute value of the radar cross section is less in Figure 2a than in Figure la b) the width of the maxima in Figure 2a is less than in Figure la .
The radar absorber thus not only ensures reflection damping with respect to the maximum strength of the detected signal, but rather also substantially reduces the width of the maxima.
In the dynamic radar cross sections (revolution period of the radar 4.2 seconds in each case) according to Figures lb and 2b have the result that a) in Figure 2b, the absolute values of the radar reflections in Figure 2b are generally reduced in relation to Figure lb, b) in Figure 2b, the number of the radar reflections above 200 units on the vertical axis is less (on average, more than every second radar reflection of the wind power plant is absent).
Due to the frequent absence of the radar reflections of the wind power plant, the signal processing unit of a radar can recognize that this is not a real target, but rather merely an apparent target which has to be filtered out.
Figure 3a shows a cross-sectional illustration of an embodiment of the passive radar absorber according to the invention, which is integrated in the rotor blade. The surface of the rotor blade is located on the left side. All elements of the absorber are embedded in the fiber-reinforced plastic material of the rotor blade and enclosed thereby.
The layer VS close to the surface (for example, a fibrous web, cloth, knitted fabric, or a film) with a defined electric sheet resistivity of 100 to 800 ohm/square is located at a distance of 2 to 5 mm below the surface. The layer ES far removed from the surface (electrically conductive base surface of the absorber) is provided at a distance of 5 to 16 mm below the layer VS close to the surface.
Figure 3b shows the frequency response of the associated reflection coefficients for this absorber. As can be seen therefrom, the absorber is optimized in this embodiment for the frequency of 2.9 GHz.
Figure 4 shows a rotor blade R according to the invention, from which in particular the distribution of the absorber in the surface of the rotor blade can be inferred.
Two discrete surface sections ABI, AB2, on which the radar absorber is integrated into the rotor blade R, can be seen in the 3-D illustration of Figure 4a. Both surface sections are located on the rotor blade edges, wherein one, AB2, is on the front edge and the other, ABl, is on the rear edge.
As can be seen in the sectional illustration according to Figure 4b, the absorber AB2 is drawn over the rotor edge and is distributed asymmetrically in this case on the lower and upper sides of the rotor blade (the absorber ABl in the surface section on the rear edge is not shown in Figure 4b). An arrangement of the absorbers ABl, AB2 in the immediate surroundings of the blade edge, as is shown in general in Figures 4a-c, is particularly advantageous for the generation of the effect according to the invention. An arrangement of the absorbers exclusively on the blade edges as shown in Figure 4 is already sufficient for the generation of the effect according to the invention. The blade edges are not provided with the absorber in the entire length thereof.

Claims (5)

1. Rotorblad (R) af fiberforstærket kunststof til et vindkraftanlæg, hvilket rotorblad har en radar absorber, der er indlejret i det fiberforstærkede kunststof, og som er kendetegnet ved, at den integrerede radar absorber afdækker flere diskrete fladeområder (ABI, AB2) af rotorbladet (R) uden at afdække hele rotorbladets (R) overflade, - fladeområderne (ABI, AB2) kun strækker sig over en del af rotorbladets (R) længde, og et afsnit af rotorbladets kanter befinder sig i i det mindste et af de diskrete fladeområder (ABI, AB2), - den integrerede radar absorber har et overfladenært lag (VS) med en defineret elektrisk flademodstand på 100 til 800 ohm/kvadrat, hvilket lag befinder sig i en dybde af 2 til 5 mm under overfladen, - den integrerede radar absorber har et overfladefjernt lag (ES) med en defineret elektrisk flademodstand på maksimalt 50 ohm/kvadrat i en afstand til det overfladenære lag (VS) på 5 til 16 mm.A fiber-reinforced plastic rotor blade (R) for a wind turbine, said rotor blade having a radar absorber embedded in the fiber-reinforced plastic, characterized in that the integrated radar absorber covers several discrete surface areas (ABI, AB2) of the rotor blade (R) without uncovering the entire surface of the rotor blade (R); ABI, AB2) - the integrated radar absorber has a surface-close layer (VS) with a defined electric surface resistance of 100 to 800 ohms / square, which layer is at a depth of 2 to 5 mm below the surface, - the integrated radar absorber has a surface-removing layer (ES) with a defined electric surface resistance of maximum 50 ohms / square at a distance from the surface-close layer (VS) of 5 to 16 mm. 2. Rotorblad ifølge krav 1, kendetegnet ved, at der i samtlige diskrete fladeområder (ABI, AB2) hver gang befinder sig et afsnit af rotorbladets kanter.Rotor blade according to claim 1, characterized in that in each discrete surface area (ABI, AB2) there is a section of the edges of the rotor blade each time. 3. Rotorblad ifølge et af de foregående krav, kendetegnet ved, at det overfladenære lag (VS) har en orienteringsretning i fladen, som bevirker en retningsafhængig fladeledeevne.Rotor blade according to one of the preceding claims, characterized in that the surface-close layer (VS) has an orientation direction in the surface which causes a direction-dependent surface conductivity. 4. Rotorblad ifølge et af de foregående krav, kendetegnet ved, at det overfladenære lag (VS) består af en vlies, et væv, et strikket stof eller en folie.Rotor blade according to one of the preceding claims, characterized in that the surface-close layer (VS) consists of a fleece, a tissue, a knitted fabric or a foil. 5. Rotorblad ifølge et af de foregående krav, kendetegnet ved, at det overfladefjerne lag (ES) består af en vlies, et væv, et strikket stof eller en folie.Rotor blade according to one of the preceding claims, characterized in that the surface-removing layer (ES) consists of a fleece, a tissue, a knitted fabric or a foil.
DK09749491.8T 2008-05-21 2009-05-16 ROTOR SHEET WITH INTEGRATED RADAR ABSORBER FOR A WINDOW POWER PLANT DK2297815T3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102008024644.1A DE102008024644B4 (en) 2008-05-21 2008-05-21 Rotor blade with integrated radar absorber for a wind turbine
PCT/DE2009/000689 WO2009140949A1 (en) 2008-05-21 2009-05-16 Rotor blade having radar absorber integrated therein for a wind power plant

Publications (1)

Publication Number Publication Date
DK2297815T3 true DK2297815T3 (en) 2018-01-08

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Country Status (7)

Country Link
US (2) US8932025B2 (en)
EP (1) EP2297815B1 (en)
BR (1) BRPI0913066B1 (en)
DE (1) DE102008024644B4 (en)
DK (1) DK2297815T3 (en)
ES (1) ES2650805T3 (en)
WO (1) WO2009140949A1 (en)

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GB0907010D0 (en) 2009-04-23 2009-06-03 Vestas Wind Sys As Improvements in or relating to composite structures
GB0919198D0 (en) 2009-11-02 2009-12-16 Qinetiq Ltd Wind turbine blades
GB2484941A (en) 2010-10-26 2012-05-02 Vestas Wind Sys As Material with radar absorbing circuit analogue elements for surface application to a wind turbine component
DE102010050591A1 (en) 2010-11-05 2012-05-10 Eads Deutschland Gmbh Wind farm, wind turbine in a wind farm, as well as operation control for this
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DE102010053369A1 (en) * 2010-12-03 2012-02-16 Eads Deutschland Gmbh Rotor blade for a wind turbine, and combination of a radar station and a wind turbine
FR2968729B1 (en) * 2010-12-08 2013-01-04 Ineo Defense IMPROVED FURTIVE WIND-EOLIAN BLADE AND WINDMILL WITH SUCH A BLADE
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US20130017096A1 (en) * 2011-07-13 2013-01-17 Charles Holley Reducing radar interference from wind turbines
US9140234B2 (en) 2012-01-11 2015-09-22 General Electric Company Wind turbine rotor blades with reduced radar cross sections
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CN106772440B (en) * 2017-01-12 2023-09-19 杭州赛尤新能源科技有限公司 Wind measuring system adopting variable-frequency laser wind measuring radar and variable-frequency control method

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Also Published As

Publication number Publication date
BRPI0913066B1 (en) 2020-10-20
US20110129352A1 (en) 2011-06-02
US8932025B2 (en) 2015-01-13
BRPI0913066A2 (en) 2015-10-13
DE102008024644A1 (en) 2009-12-03
ES2650805T3 (en) 2018-01-22
US20150153448A1 (en) 2015-06-04
EP2297815A1 (en) 2011-03-23
DE102008024644B4 (en) 2018-07-26
EP2297815B1 (en) 2017-10-04
WO2009140949A1 (en) 2009-11-26

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